Heat exchanger



FIG. 1 is a top-plan view of a heat-exchanger, showing our new design;

FIG. 2 is a front-elevational view thereof;

FIG. 3 is a right-side elevational view thereof;

FIG. 4 is a rear-elevational view thereof;

FIG. 5 is a left-side-elevational view thereof; and

FIG. 6 is a bottom-plan view thereof.

The exhaust tube has been broken away in the middle in FIGS. 1, 2, 4,and 6, for convenience of illustration and to indicate indeterminatelength.

The ornamental design for a heat exchanger, as shown.